Blockchain as a form of distributed ledger enabling the renowned cryptocurrency Bitcoin has been in the spotlight since the late 2000s. The early discussions on its practical implementation were conducted mainly for the banking and finance industries with a promising narrative. Alongside the recent surge in the interest for the technology for a wide-range of possible applications such as smart contracts, crypto-assets, tokenization, secure transaction recording, peer-to-peer (P2P) trade, and transparent governance, its potential for the Built Environment (BE) has started to come more frequently into question. These discussions often contain a tone of caution, nevertheless, hinting the challenges for the technology in the BE context. This chapter is aimed at summarizing those opportunities and challenges for blockchain in the BE with a particular emphasis on its potential influence on trust, transparency and cybersecurity. Directions of future research are also provided contributing to the cyber-physical convergence in Construction 4.0.

With the ever-growing digitalisation of the built environment, specifying information requirements (IR) is crucial to control the Building Information Modelling (BIM) data. However, the way of encoding these requirements is subject to a wide range of possibilities, making it difficult for the users to choose the most suitable method. The paper presents a comparative analysis of methods to define IR based on document study and expert group discussions. The study covers Data Dictionaries (ISO12006), Information Delivery Manual (IDM), IFC Property templates, Information Delivery Specification (IDS), Level of Information Need, Model View Definition (mvdXML), and Product Data Templates (PDT), as well as other, non-standardised methods such as Linked Data with SHACL. The comparison is based on criteria from the review of use-cases and covers aspects such as value constraints, properties of fields, geometry representation, metadata, expressiveness and dependency. The paper concludes that no single method covers all the discussed aspects, and selection should be made consciously based on a purpose. The results are relevant to information managers to understand the relations and differences between IR methods, suggest standardisation bodies a way forward to harmonise, integrate or differentiate the standards, and provide a framework for evaluating IR methods.